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There are a few interstate bans on some plants, but in general it sounds like fun! I'd be too worried about the plants getting beat up in transit, though. Do you have any words of wisdom on shipping packaging? Does volume affect whether you're considered as a business vs. friends trading, etc?

Large garden centres ship plants and seedlings every day. If you use packing material like shredded paper or old bubble wrap, etc, in between the pots so they stay upright and make sure to mark the top on the outside of the box, shipping and courier companies would do a fine job I am sure of shipping your plants. The main thing I would think would be making sure they were moist enough to keep them from drying out during shipment. However, the vermiculite in MM holds moisture for quite some time so if you make sure the plants are well watered and then put pot and all in a ziplock baggie they should be fine for several days. I have had plants shipped ground from a Richters in Toronto to where I live in central BC. That is 5 days and they were fine. There was nothing fancy in the box at all except for some of those packing beads to keep the plants upright. They had a tag on the outside of the box saying "Live plants. This side UP."

bear in mind please:whenever you send live plant material to another location:1) it might become an invasive species.2) you might be sending insect, mite, nematode, fungus, bactera, etc. that could be the next epidemic for that region.

So you might think it's fun or cool to send your favorite cultivar to your friends afar. The local ecology may disagree. Most problematic introductions are unintentional. And they are difficult or (usually) impossible to undo.